页面开发技巧 asp.net控件事件 以维持滚动位置 客户端回调

1、提交后的回发时能自动进入上次的当前位置

例如，如果数据项导致大型页回发，则最终用户需要将页滚动到此前正在编辑它们的位置，才能继续。页开发人员通过以下方法可以简单地标记窗体，以维持滚动位置：在 @Page 指令中将 MaintainScrollPositionOnPostBack 属性设置为 true，或在 Web.config 中进行此设置，以应用于应用程序中的所有页。

2、Button 控件的 OnClientClick 属性允许您在此按钮被单击时以编程方式运行客户端脚本。该按钮呈现客户端 onclick 属性以及按钮自身的 Javascript。

3、用于控件的一个令人惊喜的新功能是“客户端回调”，该功能允许控件向服务器执行带外请求以获取附加数据，而不发送整页。此功能依赖于用于回调处理（通常通过 XMLHTTP）的浏览器支持，该支持由 SupportsClientCallbacks 在浏览器功能中指定。

其实一般的无刷新页面就可以使用客户端回调来实现，只有复杂的才需要使用AJAX等

<% @ Page Language = " C# "  AutoEventWireup = " true "  EnableEventValidation = " false "  CodeFile = " CallBackEventHandler_cs.aspx.cs "  Inherits = " CallBackEventHandler_cs "   %>

<! DOCTYPE html PUBLIC  " -//W3C//DTD XHTML 1.0 Transitional//EN "   " http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd " >

< html xmlns = " http://www.w3.org/1999/xhtml "   >
< head runat = " server " >
    < title > Client CallBack </ title >
</ head >
< body >
< form id = " Form1 "  runat = " server " >

    < h3 > Cascading DropDownLists Using ICallBackEventHandler </ h3 >
    < asp:DropDownList ID = " ParentDropDown "
    onchange = " GetChildren(this.options[this.selectedIndex].value, 'ddl'); "    
    Runat = " server " >
      < asp:ListItem Text = " Item 1 "   />
      < asp:ListItem Text = " Item 2 "   />
      < asp:ListItem Text = " Item 3 "   />
    </ asp:DropDownList >
    < asp:DropDownList ID = " ChildDropDown "  AutoPostBack = " true "  style = " visibility:hidden "  Runat = " Server " >
     < asp:ListItem Text = " Child Item "   />
    </ asp:DropDownList >
    < br  />< br  />
    < asp:Label ID = " Label1 "  runat = " server " />

    < script type = " text/javascript " >

   function ClientCallback(result, context) {

      var childDropDown = document.forms[0].elements['<%=ChildDropDown.UniqueID%>'];

      if (!childDropDown){
         return;
      }

      childDropDown.length = 0;

      if (!result){
          return;
      }
      
      var rows = result.split('|'); 
      for (var i = 0; i < rows.length; ++i){
         var option = document.createElement("OPTION");
         option.value = rows[i];
         option.innerHTML = rows[i];     
         childDropDown.appendChild(option);
      }
      
      childDropDown.style.visibility = "visible";
   }

   function ClientCallbackError(result, context) {
      alert(result);
   }

    </ script >

</ form >
</ body >

</ html >

 

 

 

//----------------------------------------------------------------------- // This file is part of the Microsoft .NET SDK Code Samples. // // Copyright (C) Microsoft Corporation. All rights reserved. // //This source code is intended only as a supplement to Microsoft //Development Tools and/or on-line documentation. See these other //materials for detailed information regarding Microsoft code samples. // //THIS CODE AND INFORMATION ARE PROVIDED AS IS WITHOUT WARRANTY OF ANY //KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE //IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A //PARTICULAR PURPOSE. //----------------------------------------------------------------------- using System; using System.Web.UI; public partial class CallBackEventHandler_cs : System.Web.UI.Page, ICallbackEventHandler { private string _callbackResult; private void Page_Load(object source, EventArgs e) { String callBack = Page.ClientScript.GetCallbackEventReference(this, "arg", "ClientCallback", "context", "ClientCallbackError", false); String clientFunction = "function GetChildren(arg, context){ " + callBack + "; }"; Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "GetChildren", clientFunction, true); if (Page.IsPostBack && !Page.IsCallback) { Label1.Text = "You Selected: " + Request.Form["ParentDropDown"] + ": " + Request.Form["ChildDropDown"]; } } public string GetCallbackResult() { return _callbackResult; } public void RaiseCallbackEvent(string eventArgument) { switch (eventArgument) { case "Item 1": _callbackResult = "One|Two|Three"; break; case "Item 2": _callbackResult = "Four|Five|Six"; break; case "Item 3": _callbackResult = "Seven|Eight|Nine"; break; default: _callbackResult = ""; break; } } }

 

 

 

source http://www.cnblogs.com/firstyi/archive/2006/11/13/559156.html